248
1.70
1.65
[)
1.60
tow
a:
1.55
::J
~
w 1.50
D.
::E
w
IoJ
1.45
21 b)
«
~
w
1.40
I0
D.
1.35
0
-1
-2
1960
1965
1970
1975
1980
1985
1990
TIME (years)
Figure 29: (a) Potential temperature at 0"2 = 37.16kgm- 3 for the deepest layers of the
Labrador Sea. From Lazier and Gershey, 1991. (b) Temperature anomaly (OC) at 0-200
m in the Irminger component of the Labrador Current. From Borovkov and Tevs, 1991.
- 700 km in 8 or 20 months at mean speeds of 1-3 cmls - is an order
of magnitude faster than the published spreading rates, as these authors
point outThey suggest that the two areas might even be regarded as the
same entity from the viewpoint of LSW formation and spreading.
(ii) Evidence on the trans-Atlantic spreading rate of LSW is provided from two main studies.
In his carefully-compiled salinity series from the Rockall Channel, Ellett describes an abrupt, 7- standard deviation drop in salinity in 1990-91
in the depth layer [1600-1800 m] occupied by LSW in the East Atlantic,
[Figure 31, from Ellett, 1993]. He interprets this extreme event as indicating the sudden arrival at the eastern boundary of the fresh LSW vintage